At the starting of the 21st century, the awareness for electric and other alternative fuel vehicles has increased due to growing concern over the problems associate with hydrocarbon-fueled vehicles harming to the environment caused by their CO2 emissions and realizing the benefit that electrical vehicles (EV) offers as it can greatly increase Mile Per Gallon Equivalent (MPGe). However the shortcoming of electrical vehicles (EV) is still the limitation of driving range on their fully charged batteries and long charging time. The range is usually between 60 miles to 300 miles per charge while charging time is between 2 hours to 10 hours or more. Therefore, a high power EV fast charger is the best solution for solving the feasibility of Electric Vehicle (EV).
Traditional high power EV fast charger uses AC grid as power source. It converts AC grid power to DC power when charging EV battery. It suffers two major drawbacks: (1) since many charging stations are connected to an AC grid power feeder, when they operate at same time, particularly during on-peak hour, the AC grid power feeder may not have enough power supporting all EV chargers; (2) If AC grid power is produced by coal or other fossil fuel, the Mile Per Gallon Equivalent (MPGe) of EV is reduced significantly, which severely cuts the benefit of EV itself and even defeat the purpose of using EV. In order to mitigate power shortage on peak hour and environmental pollution caused by production of AC grid power, it is ideal to build solar energy based high power EV fast chargers.
Currently there are two different prior art configurations of solar energy based EV fast charger: (1) It uses solar energy directly to charge EV battery (DC/DC) as disclosed in U.S. Pat. Application US 2010/0181957 A1 (2) It inverts solar energy to AC power (DC/AC) first and then converts AC power back to DC (AC/DC) charging battery as disclosed in U.S. Pat. Application US 2013/0127395 A1, U.S. Pat. Application US 2011/0276194 A1 and U.S. Pat. No. 9,153,847 B2. Both configurations suffer major deficiencies. For configuration (1), the usage of solar energy is low because the unused solar energy is wasted when no EVs are in charging process. For configuration (2), the conversion efficiency of solar energy is low due to two stage conversion (the system inverts solar power to AC grid power (DC/AC) first, and then converts AC back to DC charging EV battery (AC/DC)) and the cost of the system is very high because it has two high power converters (a solar power conversion system (PCS) and an EV fast charger). Since high power EV fast charger itself contains major components of solar power system, it is desirable to add solar energy generation function into EV fast charger, namely, combining EV fast charger and solar energy generation into one system, and using single stage instead of two stage power conversion to obtain a low cost and high efficient solar energy based EV fast charging station (EVFCS).
The prior art has not set forth a low cost and high efficiency EV fast charging station with solar energy system and method that can capture and use as much solar energy as possible to fast charge EV battery and at same time produce AC grid power. The object of this invention is to provide a low cost and high efficient solar energy based high power EV fast charging station by combining EV fast charger and solar energy generation into one system which is capable of charging any EV battery with various voltage ranges by solar energy and at the same time converting solar energy to AC grid power.